The paper reports the temperature-dependent time domain terahertz spectroscopy of premium aqua-soluble and plastic explosives such as NHNO, TNT, and RDX between 0.1 and 2.2 THz. Tunable terahertz radiation was generated using ZnTe crystal as a source, and a photoconductive antenna was used as a detector. The temperature-dependent study was carried out between 30°C and 200°C in a specially designed oven. The signature peaks of RDX and TNT present at 0.82 and 1.60 THz, respectively, show a strong redshift, whereas the NHNO molecule shows a comparatively small shift. The high-temperature-based redshift phenomenon is just the opposite of the blueshift recorded at low temperatures. In addition, the temperature-dependent absorption coefficient data of these molecules support the change in the concentration of the NO molecule. We have also ascertained the temperature-dependent refractive indices of these molecules between 0.1 and 2.0 THz, which confirms the effect of temperature on the refractive indices. Finally, the signature peak of RDX with respect to the reduction in the weight concentration of RDX in the Teflon matrix was studied at 0.82 THz.
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http://dx.doi.org/10.1364/AO.57.008743 | DOI Listing |
As a noninvasive optical method, terahertz time-domain spectroscopy (THz-TDS) has been applied to diagnose the plasma parameters. Previous reports mainly focused on the phase and amplitude changes of THz waves induced by the plasma, while the terahertz polarization characteristics were rarely reported. In this paper, in addition to the plasma electron density and terahertz transmittance, we further applied the terahertz time-domain polarimetry (THz-TDP) method to diagnose the terahertz polarization rotation angles induced by an argon inductively coupled plasma (ICP).
View Article and Find Full Text PDFSci Rep
January 2025
Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, 119991, Russia.
Vanadium dioxide ([Formula: see text]) is a favorable material platform of modern optoelectronics, since it manifests the reversible temperature-induced insulator-metal transition (IMT) with an abrupt and rapid changes in the conductivity and optical properties. It makes possible applications of such a phase-change material in the ultra-fast optoelectronics and terahertz (THz) technology. Despite the considerable interest to this material, data on its broadband electrodynamic response in different states are still missing in the literature.
View Article and Find Full Text PDFSensors (Basel)
January 2025
Department of Information Engineering, Electronics and Telecommunications (DIET), "La Sapienza" University of Rome, 00184 Rome, Italy.
This research proposes an all-metal metamaterial-based absorber with a novel geometry capable of refractive index sensing in the terahertz (THz) range. The structure consists of four concentric diamond-shaped gold resonators on the top of a gold metal plate; the resonators increase in height by 2 µm moving from the outer to the inner resonators, making the design distinctive. This novel configuration has played a very significant role in achieving multiple ultra-narrow resonant absorption peaks that produce very high sensitivity when employed as a refractive index sensor.
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January 2025
Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland.
Terahertz radiation patterns can be registered using various detectors; however, in most cases, the scanning resolution is limited. Thus, we propose an alternative method for the detailed scanning of terahertz light field distributions after passing simple and complex structures. Our method relies on using a dielectric waveguide to achieve better sampling resolution.
View Article and Find Full Text PDFInorg Chem
January 2025
College of Physics, Qingdao University, National Demonstration Center for Experiment Applied Physics Education (Qingdao University), Qingdao Broadband Terahertz Spectroscopy Technology Engineering Research Center (Qingdao University), Qingdao 266071, China.
As promising optoelectronic functional materials in the short-wavelength spectral region, such as ultraviolet (UV) and deep UV, phosphates have recently received increased attention. However, phosphate materials commonly suffer from limited birefringence owing to the highly symmetrical PO tetrahedra. We herein report a layered tin(II) phosphate with improved birefringence.
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